Regional anesthesia in ruminants: limitations of data extrapolation between cattle and reindeer

The purpose of this analytical study was to critically evaluate the possibility and limitations of extrapolating regional anesthesia data from cattle and other domestic ruminants to reindeer ( Rangifer tarandus ). The material included Russian and international publications on veterinary anesthesia, operative surgery, epidural and local anesthesia, procedural analgesia, chemical immobilization and perioperative monitoring in cattle, sheep, reindeer and other cervids. The analysis separated four levels of evidence: clinical and educational data obtained in cattle, comparative data from small ruminants, direct publications on Rangifer , and extrapolative evidence from other Cervidae. The results show that cattle should not be considered a universal model for reindeer when selecting injection sites, local anesthetic volumes, doses, expected spread of epidural solution or criteria for assessment of block success. The main limitations include differences in anatomical landmarks, body mass, epidural space scale, handling conditions, stress responsiveness, seasonal physiology, field immobilization, oxygenation status and the absence of validated pain assessment tools for reindeer. The available literature on reindeer is focused mainly on medetomidine-ketamine immobilization, reversal with atipamezole, hypoxemia during field anesthesia, meloxicam pharmacokinetics and behavioral assessment after castration. Direct evidence on regional anesthesia in reindeer is scarce and is limited to individual clinical reports of ophthalmic blocks and paravertebral analgesia, as well as studies of local anesthesia during clamp castration. Therefore, protocols developed for cattle may be used only as preliminary research hypotheses. Clinical implementation in Rangifer requires species-specific studies of anatomical access, minimum effective volume, duration of sensory block, severity of motor block, systemic safety, oxygen support and recovery monitoring under field conditions. A staged validation strategy is proposed: anatomical justification, dose and volume testing, sensory and motor block assessment, comparison of local anesthetics with different duration of action, and field evaluation using behavioral and telemetry-based recovery criteria.